Experimental Investigation of Steam Ejector System With an Extra Low Generating Temperature

A steam ejector system is environmentally friendly but limited to utilizing thermal energy with a temperature typically ranging from 100 °C to 200 °C. As the steam generating temperature decreases, the utilization of the thermal energy from such a low-temperature heat source becomes very challenging. In this investigation, an experimental steam ejector system was designed and constructed to investigate the performance of the ejector system with water as the working fluid at steam generating temperatures ranging from 40 °C to 60 °C. A convergent nozzle and a de Laval nozzle were used in the steam ejector as the primary nozzles, respectively. The experimental results show that the steam ejector at a generating temperature ranging from 40 °C to 60 °C can function. The performance of the convergent nozzle is a little better than that of the de Laval nozzle in most cases at the given working condition. For power plant or desalination system applications, the system coefficient of performance (COP) of the ejector with convergent nozzle could reach 3.06 when the steam generating temperature is 40 °C and the evaporator temperature is 25 °C. For refrigeration application, the ejector with a de Laval nozzle can achieve a system COP of 0.21 and 0.4 at a generating temperature of 60 °C. The results of this investigation enabled a better understanding of system performance characteristics in a steam ejector system at a generating temperature below 100 °C.